1998 Volume 47 Issue 9 Pages 570-576
The corrosion resistance and cytocompatibility of two high N-bearing austenitic stainless steels as well as SUS 316L were evaluated in a simulated physiological environment. Potentiodynamic polarization measurements and analysis of released metal ions from alloy specimens immersed in 0.9% NaCl solution were made to evaluate the corrosion resistance. The surface of the alloys was characterized with X-ray photoelectron spectroscopy (XPS). Cell growth of human gingival fibroblasts was examined under culture conditions on these alloy surfaces. The pitting potential of the high N-bearing Fe-Cr-Mn-Mo alloy was higher than that of high N-bearing Fe-Cr-Mn alloy and SUS 316L. CrN formed in the outer region of the passive film and N enriched at the alloy surface under the passive film may be effective in improving pitting corrosion resistance. The present study demonstrated a correlation between corrosion resistance and metal-induced cytotoxity. The amount of released Fe and Cr ions from high N-bearing Fe-Cr-Mn alloy was approximately one order of magnitude higher than that from high N-bearing Fe-Cr-Mn-Mo alloy and SUS 316L. The cell growth rate on the high N-bearing Fe-Cr-Mn alloy was markedly depressed because of the large amount of released metal ions. The characteristics of the high N-bearing Fe-Cr-Mn-Mo austenitic stainless steel such as non-magnetism, high localized corrosion resistance, and excellent cytocompatibility meet the requirements for use as an implant material.